1. Field of the Invention
The general field of the invention relates to plasma chambers and, more specifically, plasma chambers used in the fabrication of microchips, LCD panels, solar cells, etc.
2. Related Arts
Various plasma chambers have been used in the art for fabrication of semiconductor wafers, substrates for LCD panels, solar cells, etc. In this context, it is possible to divide such chambers into three categories depending on where the plasma is generated. In situ plasma chambers are those where the plasma is generated immidiately above the substrate that is being proccesed and where the plasma can directly contact the substrate. Example of such a chamber is provided in the prior art section of U.S. Pat. No. 4,123,316. Such arranegements are usually implemented when the plasma is used for the processing of the substrate. Remote plasma chambers are those where the plasma is generated remotely from the chamber, but a conduit is provided to transfer the plasma species onto the chamber where the substrate is processed. Example of such an arrangement is provided in, e.g., German patent application DE 19914132559, published in 1993 and U.S. Pat. No. 4,138,306. Such arrangements are usually implemented when the plasma species are used to clean the chamber where the substrate is processed, but may also be used for substrate processing. A third category is quasi-remote plasma chambers, where the plasma is generated in the same chamber where the substrate is processed, however a divider is provided between the section where the plasma is generated and the area where the wafer resides. In this manner, species from the plasma may drift towards the substrate, but the plasma cannot contact the substrate. Examples of such an arrangement are shown in U.S. Pat. Nos. 4,123,316 and 6,192,828. Quasi-remote plasma may also be implemented without having the divider, by simply having a plasma generation source that is positioned remotely from the substrate location. An example is provided in U.S. Pat. No. 4,232,057.
Remote plasma-assisted chemical vapor deposition is one application of remote plasma chamber technology. It can generally be used to deposit thin films at lower temperature and can provide high film quality, such as stoichiometric film, and excellent conformity by controlling the gas phase reaction pathway and creating desired gas species through selective gas plasma excitation. Since the substrate is placed remotely from the plasma glow region, plasma damage on the substrate is avoided. However, gas dissociation reaction is decreased due to minimal ion bombardment and the decay of radicals, which leads to a lower deposition rate. Quasi Remote Plasma CVD may be used to enhance deposition rate while maintaining the above advantages by increasing radical density by, e.g., shortening the path from the plasma to the wafer to avoid decay of radicals.
On the other hand, direct plasma is sometimes necessary for film formation, for example, when specific film properties such as high compressive stresses are required. Such film properties may be achieved by in situ plasma, due to its strong ion bombardment effect. Also, in order to efficiently perform a plasma treatment on substrate or deposited film surface for improving interface adhesion and film stability for device reliability in most of Cu interconnection processes, direct plasma is needed because of high radical and ion density. Furthermore, in-situ plasma is more effective than remote plasma for high carbon containing materials CVD reactor clean.
As can be understood from the above, conflicting process requirements necessitate seemingly incompatible chamber designs. While some processes require the plasma to be generated remotely from the substrate, others require the plasma to be generated so as to contact the substrate. Therefore, what is needed is a reactor comprising both remote or quasi-remote and direct plasma capability. Such an arrangement may be useful not only for forming film with satisfactory film properties, but also for performing plasma treatment for device reliability and effective reactor cleaning. For further related information the reader is encouraged to review the following publications: U.S. Pat. No. 5,648,175, U.S. Pat. No. 6,124,003, U.S. Pat. No. 6,192,828, U.S. Pat. No. 6,245,396, U.S. Pat. No. 6,892,669, U.S. Pat. No. 6,427,623, U.S. Pat. No. 6,886,491, U.S. Pat. No. 6,499,425, JP 53-91664, JP 2601127, JP 11-12742, JP 53-91663, JP 53-91665, and JP 53-91667.